Printed wiring boards equipped with fuses for circuit protection have been used in the past in a wide variety of electronic devices. FIG. 16 of this application illustrates a printed wiring board 101 used in a battery pack for a cellular telephone. This printed wiring board 101 is equipped with an insulating substrate 102, on which a specific wiring pattern (not shown) is formed. Also, a protection circuit 10 and a fuse 110 are mounted on this insulating substrate 102. The protection circuit 10 serves to prevent the overcharging of a battery 2, and consists of transistors or various other such electronic parts 11. The fuse 110 works as a failsafe device in the event that the protection circuit 10 should not function properly, and keeps excess current from flowing into the circuit.
The printed wiring board 101 is further provided with a charging terminal 3 for bringing electricity from a household outlet or the like to the battery 2. This electricity is supplied from a metal terminal 4, through the protection circuit 10 and the fuse 110, and to the battery 2.
As shown in FIG. 17, the fuse 110 is equipped with a package 111 composed of an epoxy resin or the like, and leads 112a and 112b which protrude in opposite directions from this package 111. The package 111 is hollow, and an electroconductive material that will melt at a specific temperature is disposed on the inside thereof. The leads 112a and 112b are electrically connected to each other via this conductive member inside the package 111.
A problem encountered with the conventional printed wiring board 101 described above was that the size of the fuse 110 was different from that of the electronic parts 11. Consequently, some chip mounters for mounting the electronic parts 11 were unable to mount the fuse 110 on the insulating substrate 102, which meant that the fuse 110 had to be mounted manually, and this lowered the working efficiency. Furthermore, the fuse 110 tended to be bulky because it had the package 111. This hindered efforts at reducing the size of the printed wiring board 101.